Hi,
The best place for your friend to do is to go to
www.ahdionline.org to see the list of the AHDI-approved schools. These schools have been evaluated by people in the MT industry (transcriptionists and business owners) to ensure that they meet the minimum standards of AHDI. Notice the word minimum, which means that even on that list there are some schools that are better than others.
Also, schools teach differently--some have more involvement with students than others. That could influence your decision also. Find the school that best fits with your learning style.
Careful research and thorough investigation is the key!